1. Technical Field of the Invention
This invention relates to substrate processing apparatus and method for processing (e.g. cleaning) a substrate, for example, semiconductor wafer, glass for LCD substrate, etc.
2. Description of the Related Art
As rotary substrate processing apparatuses of this kind, for example, Japanese Unexamined Patent Publication (kokai) No. 6-232111 and U.S. Pat. No. 5,784,797 each disclosed a rotary substrate processing apparatus that includes a rotor capable of holding a plurality of disc-shaped substrates (e.g. semiconductor wafers) paralleled with each other. In this rotary substrate processing apparatus, the rotor is equipped with holding means, for example, a plurality of holding rods for supporting the peripheries of the substrates. The substrates to be processed can be retained in the rotor where the holding rods are abutting on the peripheries of the substrates. The holding rods each has a plurality of guide grooves formed at regular intervals in positions for abutment with the substrates. Owing to the provision of these guide grooves, the rotor is capable of stable holding of the substrates.
The so-constructed rotary substrate processing apparatus sprays the substrates to be processed with specified liquid, for example, chemical liquids, deionized (pure) water, etc. while rotating the rotor at designated revolutions, in order to remove contaminants (e.g. particles, organic pollutant), resist films, oxidation films, etc. from the substrates throughout. After that, in order to dry the substrates, the rotor is rotated to blow the used liquid away from the substrates by making use of resultant centrifugal force.
However, the above rotary substrate processing apparatus is ineffective for removal requirement in accordance with the processing recipe because the revolution of the substrates does not follow the rotor rotating at a high speed.
Additionally, the holding condition between the substrates and the holding rods becomes uneven due to the presence of dimensional errors among the substrates. Therefore, the substrates cannot be processed uniformly, thereby causing a fear of deteriorating the processing efficiency of the apparatus.
Moreover, there is the possibility that at starting or stopping rotation of the rotor, the substrates slip on the holding rods to increase their abrasion, requiring an early exchange of the holding rods to new ones.